title: Pseudomonas aeruginosa AlgR phosphorylation modulates rhamnolipid production and motility.
abstract: AlgR is a key Pseudomonas aeruginosa transcriptional response regulator required for virulence. AlgR activates alginate production and twitching motility but represses the Rhl quorum-sensing (QS) system, including rhamnolipid production. The role of AlgR phosphorylation is enigmatic, since phosphorylated AlgR (AlgR-P) is required for twitching motility through the fimU promoter but is not required for the activation of alginate production. In order to examine the role of AlgR phosphorylation in vivo, a PAO1 algRD54E strain (with algR encoding a D-to-E change at position 54), which constitutively activates fimU transcription and exhibits twitching motility, was created. A corresponding PAO1 algRD54N strain (with algR encoding a D-to-N change at position 54) that does not activate fimU or twitching motility was compared to PAO1, PAO1 algRD54E, PAO1 ΔalgZ (deletion of the algZ [fimS] gene, encoding a putative histidine kinase), and PAO1 ΔalgR for swarming motility, rhamnolipid production, and rhlA transcription. PAO1 and PAO1 algRD54E produced approximately 2-fold-higher levels of rhamnolipids than PAO1 algRD54N and PAO1 ΔalgZ, thereby indicating that phosphorylated AlgR is required for normal rhamnolipid production. Examination of purified AlgR, AlgR-P, AlgR D54N, and AlgR D54E showed that AlgR-P and AlgR D54E bound preferentially to the fimU and rhlA promoters. Additionally, AlgR-P bound specifically to two sites within the rhlA promoter that were not bound by unphosphorylated AlgR. Taken together, these results indicate that phosphorylated AlgR-P has increased affinity for the rhlA promoter and is required for the coordinate activation of twitching motility, rhamnolipid production, and swarming motility in P. aeruginosa.
authors.affiliation: Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Okkotsu
authors.forename: Prince
authors.initials: P
authors.lastname: Tieku
authors.forename: Liam F
authors.initials: LF
authors.lastname: Fitzsimmons
authors.forename: Mair E
authors.initials: ME
authors.lastname: Churchill
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Schurr
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000096:biosynthesis; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006017:Glycolipids / Q000378:metabolism*; D008124:Locomotion; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D010766:Phosphorylation; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C110681:AlgR protein, Pseudomonas aeruginosa; D001426:Bacterial Proteins; D006017:Glycolipids; D050505:Mutant Proteins; D015534:Trans-Activators; C418382:rhamnolipid; D036781:Fimbriae Proteins